In a known manner, as illustrated in FIGS. 1 and 2, an electrical harness 10 includes several conductive elements 12 which are held one against another in a braided sheath 14.
For the rest of the description, the term ‘conductive element’ is at least one wire of electrically conductive material, whatever its diameter, surrounded or not by an insulating material.
Thus, one conductive element may be composed of several small section wires, coated with a plastic sheath. Alternatively, a conductive element may comprise a plurality of cables each comprising a plurality of metal wires coated with a plastic sheath, said cables being coated with a plastic sheath.
Once the conductive elements are grouped, a sheath 14 is braided around conductive elements 12 not only to keep them pressed against each other but also to protect them. Braided sheath 14 is formed from strands e.g. in cotton or polyester. It is preferably coated with a varnish.
An electrical harness 10 may pass through a partition 16 through an hole 18 formed in said partition, as illustrated in FIG. 2.
In some applications, such as when an electrical harness passes through an aircraft tank partition, it is necessary to ensure a perfect seal between harness 10 and partition 16.
According to one embodiment, hole 18 has a diameter greater than the outside diameter of electrical harness 10. To provide a seal, an annulus seal 20 is inserted between partition 16 and harness 10. It comprises a central part 22 which outer diameter is substantially identical to that of hole 18, and a flange 24, one of the faces of which is pressed against passed through partition 16. Connecting means such as bolts 26 are provided to secure annulus seal 20 to partition 16. A seal 28 in the form of a disc with a central hole is inserted between flange 24 and partition 16 as a seal between annulus seal 20 and partition 16.
Central part 22 comprises sealing means 27 for sealing between the harness and the annulus seal, or more precisely between a ring consisting of a matrix resin, which inner diameter is identical to the outer diameter of electrical harness 10, and the rest of the annulus seal.
Additionally, electrical harness 10 and annulus seal 20 are coated with a coating product 30 to provide a seal on both sides of the partition. In order to obtain the required seal, at least six layers of coating material 30 must be applied.
The application of coating material 30 to the outside of braided sheath 14 does not guarantee optimum seal since leaking paths 32 remain inside the braided tube between the conductive elements. Such leaking paths 32 are difficult to fill because the coating resin can hardly reach these sheath inner areas whatever the mode of application.